Unit 0 Bio

this shit might be cooked

Lamarck’s Theory of Evolution

Organisms can transfer acquired traits onto their descendants

Darwins Theory of Evolution

Evolution by natural selection, species evolve over time through natural selection of random organism mutations.

Homologous structures/Morphological Homologies

Structures that are similar in structure that suggest similar origins across organisms.

example of divergent evolution

Analogous Structures

Similar functioning structures with different origins
example of convergent evolution

Natural Selection

The winnowing of less fit organisms, thus leading to the greater distribution of positive hereditary traits in the next generation

Competition

The competition for limited resources drives natural selection - there are not enough resources to support the entire population, so the less fit organisms die.

Reproduction in Evolution

Reproductive success correlates to the transfer of hereditary traits, and thus to evolution. Organisms which live long enough to reproduce are the ones which are a bigger part of the next generations gene pool.

Speciation

The division of one species into several other species, often due to reproductive division.

Adaption and Variation

Variation is essential to the species due to their adaptive capabilities as species without variation are less likely to survive a change in environmental pressure. Species with variation are more likely to survive as a subgroup likely has a suitable trait.

Stability of Environment

Stable environments lead to slower rates of evolution while unstable environments have faster rates of evolution.

Fitness

The suitability for an organism/its traits for the environment.

Mutations

RANDOM changes in the genome of an organism.

Molecular Clock

Based on the evolution of species, you can approximate the time since divergence as random mutations have an occur at an approximately consistent rate.

Molecular Variation

Differences in molecules within cells leads to variation that helps adaption.

Artificial Selection

Human caused selection for specific traits.

ex: Breeding more woolly sheep, more high producing corn, dogs better suited to herding livestock.

Geographical evidence for Evolution

Evaluates the characteristics of habitats over time and how it correlates to the organisms which lived in those habitats.

Geological evidence for Evolution

Mainly describes fossil record. Supports evolution as the strata(layers of rock) get younger the higher up they are. The fossils embedded within these strata show the evolution of species from eon to eon.

Physical evidence for Evolution

Describes anatomical and structural nuances between organisms. Shows evolution through homologous, vestigial, and analogous structures.

Vestigial Structures

Structures which were once necessary in the lives of ancestors but are no longer relevant now, and thus have shrunk or become useless. Shows evolution as vestigial structures prove that organisms evolved from other organisms which lived in different time periods, and thus had different structural necessities that change over time.

BioChemical evidence for Evolution

Degree of similarity within DNA/protein sequences proves evolution as closely related organisms have more similar DNA compared to organisms that are not.

Fossil Dating

Fossils can be dated through the strata they are found in(layers of rocks whose age denote the approximate age of the fossils within them)

Carbon dating - the decay of radioactive isotopes provides a fairly accurate way to estimate fossil age as the decay is consistent and measurable.

How fundamental molecular/cellular structures prove common ancestry

All life uses DNA or RNA to store information. It is universal and thus proves that life is derived from one common ancestor. Same for ribosomes, they are used in every organism to create proteins.

Basic processes like ATP, glycolysis, and lipid bilayers are universal, again proving that evolution came from a common ancestor.

Phylogenetic Trees

Trees using assortment of data to sort species/lineages into branches of a tree, while also denoting evolution time through length of branches.

Cladograms

Denotes evolutionary proximity in a tree format through shared traits. Branch length is meaningless.

Evidence that Eukaryotes all evolved from one common ancestor

Characteristics consistent across Eukaryotes are:

Membrane bound organelles - organelles compartmentalized by membranes that clearly divide them.

Introns - useless coding portions that are cut during transcription prior to the creation of proteins. Somewhat like vestigial structures, introns are remnants of old necessities for ancestors that were evolved from.

Linear Chromosomes - all eukaryotes contain DNA compacted into several linear chromosomes.

Resistance as evidence of Evolution

Species that are the victims of human extermination, like insects, commonly evolve in real time to surpass the treatments. Insects, for example developed resistance to insecticides since their use. Bacteria are already very often resistant to penicillin. 

Pathogens as environmental pressure

They are agents which cause disease, and thus contribute to an environmental pressure as they cause organisms with resistance to them to be more fit and thus likely to pass their resistance down onto descendants.

Outgroup

The lineage/species least closely related to the other species.

Ingroup

Group being studied in a phylogenetic tree. The outgroup is determined by the ingroup.

Clades

A “branch“ of a cladogram, which includes a species and all of the lineages which evolved from it.

Speciation in Cladograms/Phylogenetic Trees

The divergence of two species at a crux in the tree shows speciation - the original species is diverging into multiple different species.

Deleterious Traits

Traits that reduce the chance of survival (fitness)

Adaptive Traits

Traits that increase the chance of survival (fitness)

Extinction

The complete death of an entire species, usually due to predation, human activities, sudden environmental changes, or loss of genetic diversity.

Typically, the species is unable to reproduce in its current environment.

How do environmental changes cause extinction

Large scale or rapid environmental changes can cause extinction, especially within species with low genetic diversity.

How Speciation vs Extinction contributes to diversity

The balance in diversity within an ecosystem reflects the balance between the two processes. The higher speciation rate, the more diverse(creation of new species) the ecosystem. The more extinction, the less diverse(deletion of species) the ecosystem.

How does extinction free up niches

The extinction of species eliminates competition in specific niches, which allows speciation of new species into those niches.

Niches

Sub-areas in the ecosystem where organisms can specialize in surviving. The anoles in the Caribbean, for example, occupied different niches(twigs, grasslands, crowns of trees, etc)

Darwin’s observations

Unity of life: organisms share many characteristics

Diversity of life: Earths species differ from each other

Adaptation: Organisms are well adapted/fit for their environments.

Embryological Homologies

Embryos of many very different organisms appear similar as embryos, proving evolution from a common ancestor.

Cetacean Evolution

Whales are documented in the fossil record as having derived from land-bound animals, and evolving more aquatic features as they began to live in the water.

Genetic Drift

Random changes in genetic proportions from generation to generation.

Gene flow

The transfer of genes from one group to another through the migration of individuals.

Nodes

Divergences in a phylogenetic tree or cladogram. Where the tree “splits“